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ACES colour management in Houdini and Clarisse

Background info

What is ACES?

The Academy Color Encoding System (ACES) is becoming the industry standard for managing color throughout the life cycle of a motion picture or television production. From image capture through editing, VFX, mastering, public presentation, archiving and future remastering, ACES ensures a consistent color experience that preserves the filmmaker’s creative vision. In addition to the creative benefits, ACES addresses and solves a number of significant production, post-production and archiving problems that have arisen with the increasing variety of digital cameras and formats in use, as well as the surge in the number of productions that rely on worldwide collaboration using shared digital image files.

ACES on Oscars.org   
Arri: Working With ACES
ACESCentral - The official hub for ACES users

OCIO ACES

Firstly you need the OCIO implementation of ACES. The acronym means Academy Color Encoding System/Specification, so it is not a software, but Houdini and Clarisse can handle any colour management system which is implemented in OCIO.

  • Download OCIO ACES colour management system:
    https://github.com/imageworks/OpenColorIO-Configs
  • Click "Clone or download" and then "Download ZIP" (sorry, but the silly github doesn`t allow to get just the stuff you need from the web interface)
  • Extract the latest version folder you find in the ZIP but without the "baked" folder inside, we really don`t need this huge data for Clarisse or Houdini (these are baked LUTs for other softwares... there is a Houdini folder, but for older versions...).
    If you have Nuke, you actually have the ACES OCIO 1.0.1, so you just have to do the next step. If you want to use the one installed with Nuke just go it`s install folder, and you can find from in the "/plugins/OCIOConfigs/configs/aces_1.0.1/"
    And yes, you can see that there is the "baked" folder, the unnecessary payload, so you can free up around 600MB by removing it, to make Nuke install more lightweight. Of course Nuke should work with ACES without this folder, I tested it, but maybe in some cases, for some reasons you will need it, so just delete it at your own risk (or remember to restore from github, if you really need it).

ACES setup in Houdini

  • In the Houdini preferences folder you can find the Houdini environment config file:
    Linux:  ~/houdiniX.X/houdini.env
    Mac:  ~/Library/Preferences/houdini/X.X/houdini.env
    Windows:   %HOME%/houdiniX.X/houdini.env                                                        
    Open this file with a text editor.                                                      
  • Put a new line at the bottom:
    OCIO = " the path to the OCIO config file, like ...../ACES_1.0.3/config.ocio , with quotes "
    More info: http://www.sidefx.com/docs/houdini/render/linear.html
3d5a335598cc334eb2a77f8cd9dff659
  • In the 3D view right click on the eye icon at the bottom left and chose Color Correction. If you see the ACES in that rolldown menu, as shown above you're ready. If not, click on the small button with the triangle and set OpenColorIO, then in that rolldown menu switch on "Enable OpenColorIO". The default linear color space is ACEScg, you can't change here, but with the next rolldown menu you can change the ODT (Output Device Transform). More info about the ACES system will arrive soon, check back later...
  • At the bottom of the Render and Composite views there are the same bars, just stowed at default, so you should click on that horizontal bar below the image area first to unhide it.

ACES setup in Clarisse

  •  In Clarisse open Preferences (Ctrl+K) and in the Color Management section check Use Ocio Config File and set the Ocio Config File to the config.ocio file in the folder you extracted somewhere, like:  ..../ACES_1.0.3/config.ocio (or the Nuke folder, described above)
  • Close the window and restart Clarisse.
  • Open the Color Management preferences again and set Scene Color Space to
    ACES > ACEScg - if you`d prefer to use industry standard settings
    ACES > ACES2065-1 - if you want to reach all colours in the spectrum and beyond... (however doing calculations with just 3 channels in such a wide gamut needs extra care, and there are impossible colors in this space)
  • Default Display Color Space to
    Output > Output sRGB - if you have a conventional monitor with sRGB color gamut
    Output > P3-D60 - if you have a wide color gamut monitor with P3 DCI option (the P3-DCI setting in the ACES list is a bit pink for most cases, it is for DCI projectors)
  • You can leave Color Picker Color Space to the default.